Answer this question truthfully
### Question: What causes Tetralogy of Fallot?
### Response: The cause of most congenital heart defects is unknown. Many factors seem to be involved.
Factors that increase the risk for this condition during pregnancy include:
Alcoholism in the mother Diabetes Mother who is over 40 years old Poor nutrition during pregnancy Rubella or other viral illnesses during pregnancy
There is a high incidence of chromosomal disorders in children with tetralogy of Fallot, such as Down syndrome and DiGeorge syndrome (a condition that causes heart defects, low calcium levels, and immune deficiency).